Treadmills have become increasingly popular as a form of exercise and therapy. Individuals may adjust the speed and resistance of the treadmill to suit their exercise requirements while avoiding inclement weather conditions and poor outside running surfaces. Dry treadmills, that is, treadmills that operate in a normal air atmosphere on the ground, are in widespread use and are typically found in health clubs, rehabilitation facilities, and home gyms. However, submerged or underwater treadmills are becoming more common as the benefits of running, jogging or walking on a dry treadmill can be combined with the natural resistance and buoyancy of water to reduce the strain and stress on the user's joints resulting from running or the use of a dry treadmill. Because the natural resistance of water provides reduced strain and stress, underwater treadmills also have been extremely beneficial for rehabilitation from injuries. As a result, these treadmills have found therapeutic use by senior citizens recovering from surgery or other injuries as well as by professional and amateur athletes.
However, underwater treadmills have a series of problems which are unique to the environment in which they operate. An underwater treadmill has unique power requirements, as it must have the ability to deliver the necessary power to the treadmill so that it can operate over a wide range of speeds while overcoming the resistive effects of water. Additional resistance is imposed each time the foot is planted on the treadmill surface which, when combined with the isolated motive power source, tends to cause a jerky motion in the treadmill. Further, by virtue of the buoyant effects of the water, there is a tendency for each foot plant to cause some water to squirt from beneath the moving continuous belt, thereby causing its tail end to lift upwards. Certain types of underwater treadmills that are electrically powered face the additional problem of isolating the electrical power source from the water. Finally, in swimming pools, exercise pools and the like, all metal objects associated with the treadmill must be connected to an electrically grounded pool bonding grid which tends to induce galvanic corrosion in the metal parts of the treadmill.
The use of underwater treadmills may be in a pool having specific water flow patterns or no specific water flow patterns. The water flow patterns in the pool can affect the resistance on the user, thereby affecting the overall exercise routine of therapy. These water flow patterns (or lack thereof) differ from one pool to another and differ based upon other conditions (including, but not limited to, the size and/or weight of the user, environmental conditions, the temperature of the water, the location of the treadmill within the pool and the chemicals within the water). These differences between one pool and another or between conditions at one time and another can limit the capabilities of an underwater treadmill and/or can result in inconsistent exercise or therapeutic results for the user. For example, an underwater treadmill operated in a large pool with side walls being positioned far from the treadmill may have an amount of resistance that will differ in comparison to one operated in a small pool having side walls positioned close to the treadmill, even though the treadmill settings are otherwise identical.
What is needed is an underwater treadmill system and an exercise method involving an underwater treadmill system that additionally enables permits control of resistance within the pool to be controlled and varied.